Семинар 20 июня 2017. В. А. Березин. Phenomenology of cosmological particle creation, Dirac sea and all that.
by: , @ Thu, 15 Jun 2017 02:16:17 +0400

20 июня 2017, в 12:45
Кафедра физики высоких энергий и элементарных частиц

В. А. Березин
(ИЯИ РАН, Москва)

Phenomenology of cosmological particle creation, Dirac sea and all that

Here we present a phenomenological model of cosmological particle
creation which allows to avoid the "vicious circle" when the purely
quantum treatment of the fields, which quanta are just the created
particle, requires imposing definite boundary conditions, while the
latter, in turn, requires solving the gravitational equations with the
created particles together with the expectation values of these very
fields as their source. We are using the hydrodynamical description of
the created particles (in Eulerian coordinates) incorporating the
"creation law" straight into the action integral with the corresponding
Lagrange multiplier. Adopting the famous result that the particle
production rate is proportional to the square of the Weyl tensor, we
showed that this induces the appearance of conformal gravity action
integral. It was tempting, then, to demand the local conformal
invariance as the fundamental law. Such a requirement, as was shown, has
very far-going consequences. It concerns, first of all, the scalar field
(terribly needed in the Standard Model). Writing for the scalar field
the simplest possible action (kinetic + mass terms only) we showed that
the local conformal invariance requires introduction of the curvature
scalar and, at the same time, the identification of this field with one
of the possible conformal factors, and such an identification induces
the self-interaction arising from the mass term and playing the role of
the quintessence. Thus, we have got the Weyl-Einstein - dilaton gravity
with the cosmological term almost for nothing. Then, we considered the
vacuum equations in our model. It is shown that, beside the "empty
vacuum" (i.e., no particles and no particle creation) which is rather
poor, there may exist the "dynamical vacuum" when particle with both
positive and negative energies are continuously creating leaving the
total energy-momentum tensor zero. This is just the Dirac sea. The
vacuum equations in this case are especially nice - the linear
combination of the Bach tensor, the Einstein tensor and the cosmological
constant.